CN103081121A - Solar cell sealing material and solar cell module produced by using same - Google Patents

Abstract

The present invention provides a solar cell encapsulating material that is easy to form a solar cell module and is excellent in adhesiveness, long-term stability of adhesive force, transparency, and heat resistance, and a solar cell module using the solar cell encapsulating material. A solar cell encapsulation material, having at least an adhesive layer ((I) layer), and comprising an ethylene-α-olefin random copolymer (A) satisfying the following (a) and satisfying the following (b) The layer ((II) layer) composed of the resin composition (C) of the ethylene-α-olefin block copolymer (B) of the condition. (a) In differential scanning calorimetry, the heat of fusion of crystals measured at a heating rate of 10°C/min is 0~70J/g, (b) In differential scanning calorimetry, at a heating rate of 10°C/min The measured crystal melting peak temperature is 100° C. or higher, and the crystal melting heat is 5 to 70 J/g.

Description

Solar cell encapsulation material and solar cell module made of same

technical field

The present invention relates to an encapsulation material for a solar cell element in a solar cell module and a solar cell module manufactured using the encapsulation material, and in detail, relates to easy formation of a solar cell module and adhesion, long-term stability of adhesive force, and transparency A solar cell encapsulation material excellent in heat resistance, etc., and a solar cell module made using the encapsulation material.

Background technique

A solar cell is a power generating device that directly converts the light energy of the sun into electricity. Solar power generation has the following characteristics: it does not need to burn oil and other fuels when generating electricity, does not produce greenhouse effect gases (such as _CO2 , etc.) Clean energy has gained attention in recent years. Solar cells are made by wiring multiple solar cell elements (batteries) in series and parallel. In addition, they are installed outdoors. Therefore, in order to avoid the influence of moisture and dust, and to withstand the impact of hail, pebbles, etc. or wind pressure, it becomes A structure in which a solar cell element is sealed in a resin and its exterior is protected with glass or a sheet is called a solar cell module. As a specific structure of the solar cell module, the following structure is mentioned: as a protective member, the surface exposed to sunlight is covered with a transparent substrate (glass/translucent solar cell sheet; front sheet) as an upper protective material, and, in addition, The back side is covered with a backside encapsulation sheet (back sheet, such as polyvinyl fluoride resin film) as a lower protective material, and the gap is covered with an encapsulation material (encapsulation resin layer) made of thermoplastics (e.g., ethylene-vinyl acetate copolymer). ) landfill.

As mentioned above, solar cell modules are mainly used outdoors for a long period of time, so various characteristics such as their composition and material structure are considered necessary. Among the above-mentioned protective components, when focusing on the encapsulation material (encapsulation resin layer), the main requirements are water vapor barrier properties, flexibility for protecting solar cell elements, and processing suitability in the manufacture of solar cell modules. Specifically, the main requirements are The following characteristics: flow characteristics for filling batteries and wiring gaps, impact resistance, heat resistance when solar cell modules heat up, transparency for sunlight to efficiently reach solar cell elements (total light transmittance, etc. ), adhesion to glass, backplane and battery, durability, dimensional stability, insulation, etc.

Currently, ethylene-vinyl acetate copolymers (hereinafter, sometimes abbreviated as EVA) are widely used as encapsulants for solar cell elements in solar cell modules (for example, refer to Patent Document 1). In addition, for the main purpose of imparting heat resistance to EVA, crosslinking using an organic peroxide as a crosslinking agent may be performed. Therefore, a process is employed in which an EVA sheet to which a crosslinking agent (organic peroxide) and a crosslinking auxiliary agent are added is produced in advance, and the obtained sheet is used to encapsulate a solar cell element.

However, when using EVA sheets to manufacture solar cell modules, depending on various conditions such as heating and pressing, there are problems as follows: acetic acid gas is generated due to thermal decomposition of EVA, which adversely affects the working environment and manufacturing equipment, or solar cell damage occurs. Corrosion of the circuit, peeling at the interface with solar cell elements, front sheet, back sheet and other components.

In response to these problems, as a solar cell encapsulation material that does not use an EVA sheet and can omit the crosslinking process, for example, a solar cell encapsulation material is disclosed in Patent Document 2, which consists of an amorphous α-olefin polymer and a crystalline A resin composition composed of a permanent α-olefin polymer, specifically, a resin composition composed of a polymer mainly composed of propylene can be used.

In addition, Patent Document 3 discloses a solar cell encapsulation material, which is characterized in that it is a polymer blend or polymer alloy composed of at least one polyolefin-based copolymer and at least one crystalline polyolefin, Specifically, a polymer blend of ethylene-methacrylic acid copolymer and general-purpose crystalline polyethylene (refer to Example 2), and a polymer blend of ethylene-methyl acrylate copolymer and general-purpose crystalline polypropylene were used. Mixture (refer to Example 3).

In addition, Patent Document 4 discloses a solar cell encapsulating material having a silane-modified resin (silane crosslinkable resin) obtained by polymerizing an ethylenically unsaturated silane compound and polyethylene for polymerization.

patent documents

Patent Document 1: Japanese Patent Application Laid-Open No. 58-60579

Patent Document 2: Japanese Patent Laid-Open No. 2006-210905

Patent Document 3: Japanese Patent Laid-Open No. 2001-332750

Patent Document 4: Japanese Patent Laid-Open No. 2005-19975

Contents of the invention

However, transparency (total light transmittance: 83.2% (see Example)) of the resin composition composed of a polymer mainly composed of propylene used in Patent Document 2 is not yet sufficient. Furthermore, polymers mainly composed of propylene have the problems of high embrittlement temperature and insufficient low-temperature properties. In addition, for the example of the polymer blend used in Patent Document 3, it is not necessarily a polymer blend with good transparency. In particular, it is difficult to balance flexibility, heat resistance, and transparency. There is a problem.

In the solar cell module filler layer of Patent Document 4, if a large amount of silane-modified resin is added in order to sufficiently express the adhesiveness with adherends such as glass and back sheets, the haze may increase and the Transparency is lowered, and there is still a problem in the balance between adhesiveness and transparency.

In addition, a method of adding a silane coupling agent is generally known in order to impart adhesiveness to the encapsulating material. There is room for further improvement.

As described above, there is no solar cell encapsulating material that is easy to form a solar cell module and has excellent adhesion, long-term stability of adhesive force, transparency, heat resistance, etc. of solar modules.

An object of the present invention is to provide a solar cell encapsulating material that is easy to form a solar cell module and has excellent adhesiveness, long-term stability of adhesive force, transparency, and heat resistance, and a solar cell module using the encapsulating material.

The inventors of the present invention have repeatedly conducted in-depth studies, and found that: the use of an adhesive layer and an ethylene-α-olefin random copolymer having specific thermal properties and an ethylene-α-olefin block copolymer having specific thermal properties The solar cell encapsulating material comprising a layer of the resin composition can simultaneously satisfy adhesiveness, long-term stability of adhesive force, transparency, and heat resistance, thereby completing the present invention.

That is, the present invention relates to a solar cell encapsulating material having at least an adhesive layer, in particular comprising a specific resin composition (Z) containing a polyethylene resin (X) and a silane-modified vinyl resin (Y). layer ((I) layer), and an ethylene-α-olefin random copolymer (A) satisfying the following (a) condition and an ethylene-α-olefin block copolymer satisfying the following (b) condition The layer ((II) layer) composed of the resin composition (C) of (B).

(a) In differential scanning calorimetry, the heat of crystal fusion measured at a heating rate of 10°C/min is 0~70J/g

(b) In differential scanning calorimetry, the crystal melting peak temperature measured at a heating rate of 10°C/min is 100°C or higher, and the crystal melting heat is 5~70J/g

According to the present invention, it is possible to provide a solar cell encapsulating material that is easy to form a solar cell module and is excellent in adhesiveness, long-term stability of adhesive force, transparency, and heat resistance, and a solar cell module using the encapsulating material.

In addition, there is no need to worry about corrosion of wiring due to acetic acid and deterioration of solar cell elements due to penetration of water vapor, and can prevent adverse effects on the working environment and manufacturing equipment, deterioration of solar cell modules, and reduction in power generation efficiency. Furthermore, with respect to the manufacturing equipment, it is applicable not only to the batch type manufacturing equipment but also to the roll-to-roll type manufacturing equipment. In addition, it is also possible to prevent a decrease in transparency during regeneration addition.

Description of drawings

Fig. 1 is a schematic cross-sectional view showing an example of the solar cell module of the present invention.

Detailed ways

Hereinafter, a solar cell encapsulating material as an embodiment of the present invention and a solar cell module produced using the encapsulating material will be described.

In this specification, the term "main component" means that other components are allowed to be contained within the range that does not interfere with the action and effect of the resin constituting each layer of the solar cell encapsulating material of the present invention. Furthermore, this term does not limit the specific content rate, but generally accounts for 50 parts by mass or more, preferably 65 parts by mass or more, and more preferably 80 parts by mass, based on 100 parts by mass of the entire constituent components of the resin composition. Components in the range of more than one part and less than or equal to 100 parts by mass.

<(I) layer>

Among the layers constituting the solar cell encapsulating material of the present invention, the (I) layer is an adhesive layer, and in the solar cell encapsulating material of the present invention, of course, it is an encapsulating layer, and is a layer that functions as an adhesive layer and a surface layer . The resin composition used in the (I) layer is not particularly limited, but in addition to adhesiveness, long-term stability of the adhesive force, transparency and heat resistance, from the viewpoint of productivity at the time of film formation of the solar cell encapsulating material, preferably A resin composition containing a polyolefin resin as a main component is used.

[Polyolefin resin]

The polyolefin-based resin used in the (I) layer is not particularly limited, but from the viewpoint of adhesiveness, transparency, productivity, and ease of industrial acquisition, it is preferable to use a polyolefin resin selected from the group consisting of ethylene-methyl methacrylate copolymers. (E-MMA), ethylene-ethyl acrylate copolymer (E-EAA), ethylene-glycidyl methacrylate copolymer (E-GMA), ethylene-vinyl alcohol copolymer (EVOH), ionomer resin (Ionically crosslinkable ethylene-methacrylic acid copolymer, ionically crosslinkable ethylene-acrylic acid copolymer), silane-modified polyolefin (silane crosslinkable polyolefin), and at least one of maleic anhydride graft copolymer A modified polyolefin resin.

In the (I) layer in the present invention, among the above-mentioned modified polyolefin-based resins, from the viewpoint of adhesiveness and heat resistance, silane-crosslinkable polyolefins or ionomer resins can be preferably used. Among crosslinkable polyolefins, silane crosslinkable polyethylene can be used more preferably. Among them, silane-crosslinkable linear low-density polyethylene (density: 0.850 to 0.920 g/cm ³ ) is particularly preferably used because of its better transparency.

The content of various monomers that modify the above-mentioned modified polyolefin resin is not particularly limited, but usually, it is 0.5 mol % or more with respect to the total amount of monomers constituting the modified polyolefin resin, preferably 1 mol % or more, more preferably 2 mol % or more, and usually 40 mol % or less, preferably 30 mol % or less, more preferably 25 mol % or less. If it is within this range, transparency is improved by lowering the crystallinity due to the copolymerization component, and since troubles such as blocking of raw material particles are less likely to occur, it is preferable. It should be noted that the types and contents of various monomers that modify the modified polyolefin polymer can be qualitatively and quantitatively analyzed by known methods such as nuclear magnetic resonance (NMR) measuring equipment and other instrumental analysis equipment.

The method for producing the above-mentioned modified polyolefin resin is not particularly limited, and it can be obtained by the following method in addition to ionomer resins, silane crosslinkable polyolefins, and maleic anhydride graft copolymers shown below, that is, A known polymerization method using a known catalyst for olefin polymerization, for example, a slurry polymerization method using a multi-site catalyst represented by a Ziegler-Natta catalyst, a single-site catalyst represented by a metallocene catalyst, Solution polymerization method, bulk polymerization method, gas phase polymerization method, etc., and bulk polymerization method using a radical initiator, etc.

The ionomer resin can be obtained by neutralizing at least a part of the unsaturated carboxylic acid component of a copolymer composed of ethylene, unsaturated carboxylic acid, and other unsaturated compounds as optional components with at least any one of metal ions or organic amines. and get. Moreover, an ionomer resin can also be obtained by saponifying at least a part of the unsaturated carboxylic acid ester component of the copolymer which consists of ethylene, an unsaturated carboxylic acid ester, and other unsaturated compounds which are optional components.

The silane-crosslinkable polyolefin can be obtained by melt-mixing a polyolefin-based resin, a silane coupling agent described later, and a radical initiator described later at high temperature, followed by graft polymerization.

The maleic anhydride graft copolymer can be obtained by melt-mixing a polyolefin-based resin, maleic anhydride, and a radical initiator described later at high temperature, and graft-polymerizing them.

Specific examples of modified polyolefin resins include E-MMA (ethylene-methyl methacrylate copolymer) under the trade name "Acryft" manufactured by Sumitomo Chemical Co., Ltd., E-EAA (ethylene-acrylic acid Ethyl Ethyl Ester Copolymer), the trade name "REXPEARL EEA" manufactured by Japan Polyethylene Co., Ltd., the trade name "BONDFAST" manufactured by Sumitomo Chemical Co., Ltd. as E-GMA (ethylene-glycidyl methacrylate copolymer), as EVOH (ethylene-vinyl alcohol copolymer) has a trade name of "Soarnol" manufactured by Nippon Synthetic Chemicals Co., Ltd., a trade name "Eval" manufactured by Kuraray Co., Ltd., a product of Dupont-Mitsui Polychemicals Co., Ltd. as an ionomer resin The name "Himilan", the trade name "Linklon" manufactured by Mitsubishi Chemical Corporation as a silane crosslinkable polyolefin, the "Admor" manufactured by Mitsui Chemicals Corporation which is a maleic anhydride graft copolymer, and the like.

(I) The melt flow rate (MFR) of the polyolefin-based resin used in the layer is not particularly limited, but the MFR (JIS K7210, temperature: 190°C, load: 21.18N) is usually used at about 0.5~100g/10min, It is preferably 2 to 50 g/10 min, more preferably 3 to 30 g/10 min of polyolefin-based resin. Here, MFR may be selected in consideration of molding processability during sheet molding, adhesiveness during packaging of solar cell elements (cells), immersion conditions, and the like. For example, when calendering a sheet, MFR is preferably relatively low, specifically about 0.5 to 5 g/10 min, in terms of handling performance when peeling the sheet from the forming roll. In the case of extrusion molding, from the viewpoint of reducing the extrusion load and increasing the extrusion amount, MFR is preferably 2 to 50 g/10 min, more preferably 3 to 30 g/10 min. Furthermore, from the viewpoint of adhesiveness and ease of immersion when sealing a solar cell element (battery), MFR is preferably 2 to 50 g/10 min, more preferably 3 to 30 g/10 min.

In the present invention, in order to obtain a solar cell encapsulating material that is easy to form a solar cell module, has excellent transparency, and is also excellent in adhesiveness and heat resistance, as the above-mentioned adhesive layer ((I) layer), it is preferable to use A layer composed of a resin composition (Z) containing a polyethylene resin (X) and a silane-modified vinyl resin (Y). In this case, the resin composition (Z) needs to satisfy the condition (a) In differential scanning calorimetry, the heat of crystal fusion measured at a heating rate of 10° C./min is 0 to 70 J/g.

[Polyethylene resin (X)]

The polyethylene-based resin (X) used in the present invention is not particularly limited as long as it is a type of polyethylene-based resin that does not prevent the above-mentioned resin composition (Z) from satisfying the above-mentioned requirement (a). Specifically, Examples thereof include low-density polyethylene, ultra-low-density polyethylene, and linear low-density polyethylene. More specifically, polyethylene-based resins with a density of 0.850 to 0.920 g/cm ³ are preferred, and linear low-density polyethylene with a density of 0.860 to 0.880 g/cm ³ is particularly preferred. In addition, polyethylene resins having different densities may be used in combination.

The low-density polyethylene-based resin preferably used in the present invention generally includes a random copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. Here, examples of α-olefins to be copolymerized with ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene. ene, 3-methyl-butene-1, 4-methyl-pentene-1, etc. In the present invention, propylene, 1-butene, 1-hexene, 1-octene, alkene. The α-olefins to be copolymerized with ethylene may be used alone or in combination of two or more.

In addition, the content of α-olefin copolymerized with ethylene is usually 2 mol% or more, preferably 40 mol% or less, more preferably 3 to 30 mol%, more preferably 5 to 25 mol%. When the content of the α-olefin is within the above range, the copolymerization component lowers the crystallinity, thereby improving the transparency, and also prevents troubles such as blocking of raw material particles from occurring, which is preferable. It should be noted that the type and content of α-olefin copolymerized with ethylene can be qualitatively and quantitatively analyzed by known methods such as nuclear magnetic resonance (NMR) measuring equipment and other instrumental analysis equipment.

The ethylene-α-olefin random copolymer may contain monomer units derived from monomers other than α-olefin. As this monomer, a cyclic olefin, a vinyl aromatic compound (styrene etc.), a polyene compound, etc. are mentioned, for example. The content of the monomer unit is 20 mol% or less, more preferably 15 mol% or less, based on 100 mol% of all monomer units in the ethylene-α-olefin random copolymer. In addition, the three-dimensional structure, branching, branching degree distribution, and molecular weight distribution of the ethylene-α-olefin random copolymer are not particularly limited, but for example, copolymers with long-chain branching generally have good mechanical properties, and also have the ability to form a sheet. Advantages such as increased melt tension (melt tension) and improved calenderability. A copolymer with a narrow molecular weight distribution polymerized using a single-site catalyst has advantages such as less low-molecular-weight components and relatively less sticking of raw material particles.

The melt flow rate (MFR) of the polyethylene-based resin (X) used in the present invention is not particularly limited, but the MFR (JIS K7210, temperature: 190°C, load: 21.18N) is generally used at about 0.1 to 100g/10min , preferably 2 to 50 g/10 min, more preferably 3 to 30 g/10 min of polyethylene-based resin. Here, MFR may be selected in consideration of molding processability during sheet molding, adhesiveness during packaging of solar cell elements (cells), immersion conditions, and the like. For example, when calendering a sheet, MFR is preferably relatively low, specifically about 0.5 to 5 g/10 min, in terms of handling performance when peeling the sheet from the forming roll. In the case of extrusion molding, from the viewpoint of reducing the extrusion load and increasing the extrusion amount, MFR is preferably 2 to 50 g/10 min, more preferably 3 to 30 g/10 min. Furthermore, from the viewpoint of adhesiveness and ease of immersion when sealing a solar cell element (battery), MFR is preferably 2 to 50 g/10 min, more preferably 3 to 30 g/10 min.

For the polyethylene-based resin (X) used in the present invention, in order for the above-mentioned resin composition (Z) to satisfy the above-mentioned condition (a), crystallization measured at a heating rate of 10°C/min in differential scanning calorimetry The heat of fusion is preferably 0 to 70 J/g. More preferably, it is 5-70 J/g, More preferably, it is 10-65 J/g. If it is within this range, the flexibility, transparency (total light transmittance), and the like of the solar cell encapsulating material of the present invention are secured, which is preferable. In addition, when the heat of crystal fusion is 5 J/g or more, since troubles such as sticking of raw material particles are less likely to occur, it is preferable.

The heat of fusion of the crystals can be measured at a heating rate of 10° C./min in accordance with JIS K7122 using a differential scanning calorimeter.

The average refractive index of the polyethylene-based resin (X) used in the present invention is usually in the range of 1.4800 to 1.5000, preferably 1.4810 to 1.4990, particularly preferably 1.4820 to 1.4980. By setting the composition ratio of the polyethylene-based resin (X) within the above-mentioned range, the average refractive index can be within the preferable range.

The average refractive index can be measured at a temperature of 23° C. using a sodium D line (589 nm) as a light source in accordance with JIS K7142.

The above-mentioned polyethylene-based resin (X) may be one type, or may be a combination of two or more types.

The method for producing the polyethylene-based resin (X) used in the present invention is not particularly limited, and a known polymerization method using a known catalyst for olefin polymerization can be employed. Examples include slurry polymerization and solution polymerization using multi-site catalysts represented by Ziegler-Natta catalysts, single-site catalysts represented by metallocene catalysts, and post-metallocene catalysts. , a bulk polymerization method, a gas phase polymerization method, etc., and a bulk polymerization method using a radical initiator, etc. are also mentioned. In the present invention, since the low-density ethylene-α-olefin random copolymer preferably used is a relatively soft resin, from the viewpoints of easiness of granulation (granulation) after polymerization and prevention of blocking of raw material particles, etc. From this point of view, it is preferable to employ a polymerization method using a single-site catalyst using a raw material with a small polymerizable low-molecular-weight component and a narrow molecular weight distribution.

Specific examples of the polyethylene-based resin (X) used in the present invention include trade names "Engage", "Affinity", and "Infuse" manufactured by Dow Chemical Co., Ltd., and trade names "TAFMER A" manufactured by Mitsui Chemicals Co., Ltd. , "TAFMER P", trade name "Karner" manufactured by Nippon Polyethylene Co., Ltd., etc.

[Silane modified vinyl resin (Y)]

The silane-modified vinyl resin (Y) used in the present invention can usually be melted at a high temperature (about 160°C to 220°C) with a polyethylene-based resin, a vinylsilane compound described later, and a radical initiator described later. Mixed and obtained by graft polymerization.

(polyethylene-based resin)

The polyethylene-based resin for obtaining the above (Y) is preferably a resin having the same composition, density, MFR, heat of crystal fusion, and average refractive index as those exemplified as the polyethylene-based resin suitable for the above-mentioned (X). .

Specifically, a polyethylene-based resin with a density of 0.850 to 0.920 g/cm ³ is preferable, and a linear low-density polyethylene with a density of 0.860 to 0.880 g/cm ³ is more preferable. In addition, the melt flow rate (MFR) is not particularly limited. Usually, MFR (JIS K7210, temperature: 190°C, load: 21.18N) is used at about 0.5 to 100 g/10 min, preferably 2 to 50 g/10 min, more preferably 3 ~30g/10min.

In addition, the heat of crystal fusion measured at a heating rate of 10° C./min in differential scanning calorimetry is preferably 0 to 70 J/g. More preferably, it is 5-70 J/g, More preferably, it is 10-65 J/g. The average refractive index is usually in the range of 1.4800 to 1.5000, preferably 1.4810 to 1.4990, particularly preferably 1.4820 to 1.4980.

Furthermore, when the polyethylene-based resin is an ethylene-α-olefin random copolymer, as the content of α-olefin copolymerized with ethylene, with respect to all the monomer units in the ethylene-α-olefin random copolymer, Usually it is 2 mol % or more, Preferably it is 40 mol % or less, More preferably, it is 3-30 mol %, More preferably, it is 5-25 mol %. When the content of the α-olefin is within the above range, the copolymerization component lowers the crystallinity, thereby improving the transparency, and also prevents troubles such as blocking of raw material particles from occurring, which is preferable.

(vinylsilane compound)

The vinylsilane compound is not particularly limited as long as it is graft-polymerized with the above-mentioned polyethylene-based resin, and for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, Vinyltriisopropoxysilane, Vinyltributoxysilane, Vinyltripentoxysilane, Vinyltriphenoxysilane, Vinyltribenzyloxysilane, Vinyltrimethylenedioxysilane , vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and at least one vinylsilane compound selected from vinyltricarboxysilane. In the present invention, vinyltrimethoxysilane is preferably used from the viewpoints of reactivity, adhesiveness, color tone, and the like.

In addition, the addition amount of this vinyl silane compound is not specifically limited, It is about 0.01-10.0 mass parts with respect to 100 mass parts of polyethylene resins used normally, More preferably, it is 0.3-8.0 mass parts, It is more preferable to add 1.0-8.0 mass parts. 5.0 parts by mass.

(free radical initiator)

The radical initiator is not particularly limited, and examples include hydrogen peroxides such as dicumyl hydroperoxide and 2,5-dimethyl-2,5-bis(hydroperoxide)hexane. ; Di-tert-butyl peroxide, tert-butyl cumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butyl peroxy)hexane, 2, Dialkyl peroxides such as 5-dimethyl-2,5-di(tert-peroxy)hexyne-3; bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide benzoyl peroxide, o-toluyl peroxide, 2,4-dichlorobenzoyl peroxide and other diacyl peroxides; tert-butyl peroxyacetate, tert-butyl peroxyacetate Butylperoxy-2-ethylhexanoate, tert-Butylperoxypivalate, tert-Butylperoxyoctanoate, tert-Butylperoxyisopropylcarbonate, tert-Butylperoxybenzoate ester, di-tert-butylperoxyphthalate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dimethyl-2, Peroxyesters such as 5-bis(benzoyl peroxide)hexyne-3; organic peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide and other ketone peroxides, or azobisisobutyl Azo compounds such as nitrile, azobis(2,4-dimethylvaleronitrile), etc.

In addition, the addition amount of the radical initiator is not particularly limited, but it is usually about 0.01 to 5.0 parts by mass, more preferably 0.02 to 1.0 parts by mass, and even more preferably 0.03 to 100 parts by mass of the polyethylene resin to be used. ~0.5 parts by mass. Furthermore, the remaining amount of the radical generator is preferably 0.001% by mass or less in each resin layer constituting the solar cell multilayer body of the present invention, and the gel fraction is preferably 30% or less.

The silane-modified vinyl resin (Y) used in the present invention and each resin layer preferably do not substantially contain a silanol condensation catalyst that promotes a condensation reaction between silanols. Specific examples of the silanol condensation catalyst include, for example, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dicaprylate, dioctyltin dilaurate, and the like. Here, substantially not containing means 0.05 mass parts or less with respect to 100 mass parts of resins, Preferably it is 0.03 mass parts or less.

Here, the reason why it is preferable not to contain a silanol condensation catalyst substantially is as follows: In the present invention, the purpose is to, under the condition that the silanol crosslinking reaction does not actively proceed, Polar groups such as silanol groups of resins and adherends (glass, various plastic sheets (plastic sheets that are suitably subjected to surface treatment such as corona treatment so that the wettability index is 50mN/m or more can be preferably used), The interaction of hydrogen bond, covalent bond, etc. of metal, etc., makes adhesiveness appear.

(Silane-modified vinyl resin (Y))

The silane-modified vinyl resin (Y) used in the present invention is usually obtained by melting and mixing the vinyl silane compound and a radical initiator at a high temperature (about 160°C to 220°C) with the above-mentioned polyethylene-based resin. It is obtained by graft polymerization. Therefore, the preferred ranges of the density and MFR of the silane-modified vinyl resin (Y) used in the present invention are the same as the preferred ranges of the density and MFR of the above-mentioned polyethylene resin.

In order for the above-mentioned resin composition (Z) to satisfy the above-mentioned condition (a), the silane-modified vinyl resin (Y) used in the present invention is preferably crystallized as measured at a heating rate of 10°C/min in differential scanning calorimetry. The heat of fusion is 0~70J/g. More preferably, it is 5-70 J/g, More preferably, it is 10-65 J/g. If it is within this range, the flexibility, transparency (total light transmittance), and the like of the solar cell encapsulating material of the present invention are secured, which is preferable. In addition, when the heat of crystal fusion is 5 J/g or more, it is less likely to cause problems such as blocking of raw material particles, which is preferable.

The average refractive index of the silane-modified vinyl resin (Y) used in the present invention is usually in the range of 1.4800 to 1.5000, preferably 1.4810 to 1.4990, particularly preferably 1.4820 to 1.4980. The average refractive index of the silane-modified vinyl resin (Y) can be adjusted to this preferred range by setting the average refractive index of the polyethylene resin used to obtain the silane-modified vinyl resin (Y) within the above-mentioned range.

The above-mentioned silane-modified vinyl resin (Y) may be one type, or may be a combination of two or more types.

At this time, when the absolute value of the difference between the average refractive indices of the above-mentioned polyethylene-based resin (X) and the above-mentioned silane-modified ethylene-based resin (Y) is 0.0100 or less, the solar cell encapsulating material of the present invention becomes hazy and transparent. A particularly excellent encapsulation material and therefore preferred. The absolute value of the above average refractive index difference is more preferably 0.0080 or less, particularly preferably 0.0060 or less.

As a specific example of the silane-modified vinyl resin (Y) used in this invention, the brand name "Linklon (LINKLON)" by Mitsubishi Chemical Corporation can be illustrated.

[resin composition]

The resin composition constituting the (I) layer mainly contains polyolefin resin, but considering various physical properties (flexibility, heat resistance, transparency, adhesiveness, etc.), molding processability, economical efficiency, etc., it may be A resin composition mainly composed of the above-mentioned modified polyolefin-based resin is used, but it is preferable to use a polyolefin-based resin other than the modified polyolefin-based resin (hereinafter referred to as "unmodified polyolefin-based resin") in combination, more preferably It is preferable to use the resin used in combination as the main component.

The unmodified polyolefin-based resin is not particularly limited, but is preferably composed of the olefin monomer constituting the above-mentioned modified polyolefin-based resin as a main component from the viewpoint of transparency. In addition, if the unmodified polyolefin resin is an ethylene-α-olefin random copolymer (A) or an ethylene-α-olefin block copolymer (B) used in the (II) layer described later, then from It is preferable from the viewpoint of the interlayer adhesiveness of the (I) layer and the (II) layer, flexibility, heat resistance, and the like.

When the modified polyolefin-based resin and the unmodified polyolefin-based resin are used in combination in the resin composition constituting the (I) layer, the mass ratio thereof is not particularly limited, but from the viewpoint of developing good adhesiveness , in terms of modified polyolefin resin/unmodified polyolefin resin, preferably in the range of 3/97 to 100/0, more preferably in the range of 5/95 to 100/0.

In addition, when a modified polyolefin-based resin and an unmodified polyolefin-based resin are used in combination in the resin composition constituting the (I) layer, the modified polyolefin-based resin and the unmodified polyolefin-based resin used are preferably Resins of the same system, such as modified polyethylene-based resins and unmodified polyethylene-based resins.

The resin composition (Z) constituting the layer (I) contains the above-mentioned polyethylene-based resin (X) and the above-mentioned silane-modified vinyl-based resin (Y). A resin composition composed of a permanent vinyl resin (Y) as the main component.

The mixing mass ratio of the above-mentioned polyethylene-based resin (X) and the above-mentioned silane-modified vinyl-based resin (Y) in the resin composition (Z) is not particularly limited, and the polyethylene-based resin (X)/silane-modified vinyl-based resin (Y) The resin (Y) mass ratio is 1-99/99-1, preferably 30-98/70-2, more preferably 60-97/40-3. If it is within this range, it is easy to adjust the content of the silane-modified vinyl resin (Y) in the (I) layer, that is, the concentration of the silane-modified group, and maintain the function of the adhesive layer that is the main function of the (I) layer. At the same time, it is relatively easy to adjust various characteristics such as flexibility, transparency, sealing performance, and heat resistance of the surface layer and sealing layer.

In addition, as long as the resin composition (Z) contains the above-mentioned polyethylene-based resin (X) and the above-mentioned silane-modified vinyl-based resin (Y), and the obtained resin composition (Z) satisfies the condition (a), each can be two more than one combination. As mentioned above, within the scope of achieving the balance of the excellent transparency, adhesiveness, and heat resistance of the solar cell encapsulating material of the present invention, the above-mentioned polyethylene-based resin ( X), the above-mentioned silane-modified vinyl resin (Y) can be composed of two or more resins with different properties such as composition, density, MFR, crystal fusion heat, and average refractive index. The resin within the preferred range of the above-mentioned composition and properties can be any One is that any resin outside this range can be used.

In the resin composition (Z), the content ratio in the case of containing polyethylene-based resin or silane-modified ethylene-based resin in which any one of the above-mentioned composition and properties is out of the preferred range is in the case of constituting the resin composition ( When the mass of all the resins in Z) is 100% by mass, the lower limit thereof is preferably 1% by mass, more preferably 2% by mass. On the other hand, the upper limit is preferably 10% by mass, more preferably 5% by mass. By making the content ratio into this range, and by making it into the said lower limit, the transparency, adhesiveness, and heat resistance of the solar cell encapsulating material of this invention can be balanced, and it is preferable.

As for the resin composition (Z), as mentioned above, it is necessary to satisfy the condition (a) in the differential scanning calorimetry, the heat of crystal fusion measured at a heating rate of 10°C/min is 0~70J/g, preferably 5~70J/g, more preferably 10~65J/g. If it exists in this range, since the flexibility, transparency (haze, total light transmittance), etc. of the solar cell encapsulating material of this invention are ensured, it is preferable. In addition, when the heat of crystal fusion is 5 J/g or more, since troubles such as blocking of raw material particles are less likely to occur, it is preferable.

In the resin composition, furthermore, within the range not departing from the gist of the present invention, for the purpose of further improving various physical properties (flexibility, heat resistance, transparency, adhesiveness, etc.), molding processability, or economical efficiency, etc. , other resins other than the above-mentioned polyolefin-based resins may be mixed. Here, as other resins, for example, other polyolefin-based resins, various elastomers (olefin-based, styrene-based, etc.), carboxyl, amino, imide, hydroxyl, epoxy, Resins obtained by modifying polar groups such as oxazoline groups and mercapto groups, and tackifying resins.

Examples of the tackifier resin include petroleum resins, terpene resins, coumarone-indene resins, rosin-based resins, or hydrogenated derivatives thereof. Specifically, as petroleum resins, there are alicyclic petroleum resins derived from cyclopentadiene or its dimer, and aromatic petroleum resins derived from C9 components. As terpene resins, terpene derived from β-pinene can be exemplified. Examples of rosin-based resins include rosin resins, terpene-phenol resins, and rosin resins such as gum rosin and wood rosin, and esterified rosin resins modified with glycerin, pentaerythritol, and the like. In addition, the tackifier resin has various softening temperatures mainly due to the difference in molecular weight, but from the compatibility when mixed with the above-mentioned polyolefin resin and modified polyolefin resin components, In terms of time-lapse color bleeding, color tone, thermal stability, etc., an alicyclic petroleum resin having a softening temperature of preferably 100 or more, more preferably 120° C. or more and preferably 150° C. or less, more preferably 140° C. or less is particularly preferred. hydrogenated derivatives.

When mixing the above-mentioned other resins into the (I) layer, usually, it is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, based on 100 parts by mass of the resin composition constituting the (I) layer.

The method of mixing these resins when forming the layer (I) using the above-mentioned polyethylene-based resin (X), the above-mentioned silane-modified ethylene-based resin (Y) and the above-mentioned other resins is not particularly limited, and they can be dry-blended with the resin in advance and then supplied to The hopper can also be supplied by melting and mixing all the materials in advance to make pellets. In addition, in the present invention, the vinylsilane compound and the radical initiator added when obtaining the silane-modified vinyl resin (Y) may remain unreacted as described above. Therefore, when the polyethylene resin (X) is mixed with When mixing the silane-modified vinyl resin (Y), it is preferable to remove volatile components using a vacuum vent.

The thickness of the (I) layer constituting the solar cell encapsulating material of the present invention is not particularly limited, but from the viewpoint of encapsulation and transparency to the uneven surface of the battery, it is usually 0.005 mm or more, preferably 0.01 mm or more, and more preferably 0.01 mm or more. 0.02 mm or more and about 0.9 mm or less, preferably 0.6 mm or less, more preferably 0.5 mm or less. In addition, from the viewpoint of encapsulation, adhesiveness, and economical efficiency for filling gaps in batteries and wiring, it is preferably about 0.01 to 0.5 mm, more preferably 0.02 to 0.4 mm, and particularly preferably 0.04 to 0.3 mm .

<(II) layer>

Among the layers constituting the solar cell encapsulating material of the present invention, the (II) layer is composed of an ethylene-α-olefin random copolymer (A) satisfying the following (a) condition and an ethylene-α-olefin random copolymer (A) satisfying the following (b) condition. A layer composed of the resin composition (C) of the α-olefin block copolymer (B).

(a) In differential scanning calorimetry, the heat of crystal fusion measured at a heating rate of 10°C/min is 0~70J/g

(b) In differential scanning calorimetry, the crystal melting peak temperature measured at a heating rate of 10°C/min is 100°C or higher, and the crystal melting heat is 5~70J/g

[Ethylene-α-olefin random copolymer (A)]

The ethylene-α-olefin random copolymer (A) used in the present invention is not particularly limited as long as it satisfies the above conditions, and generally, a random copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms is preferably used. Here, examples of α-olefins to be copolymerized with ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene , 3-methyl-butene-1, 4-methyl-pentene-1, etc. In the present invention, propylene, 1-butene, 1-hexene, 1-octene, alkene. The α-olefins to be copolymerized with ethylene may be used alone or in combination of two or more.

In addition, the content of the α-olefin to be copolymerized with ethylene is not particularly limited as long as the above condition (a) is satisfied, but it is usually 2 mol% or more, preferably 40 mol% or less, more preferably 3 to 30 mol%, even more preferably 5 to 25 mol%. If it is within this range, transparency is improved by lowering the crystallinity due to the copolymerization component, and it is also less likely to cause problems such as blocking of raw material particles, which is preferable. It should be noted that the type and content of α-olefin copolymerized with ethylene can be qualitatively and quantitatively analyzed by known methods such as nuclear magnetic resonance (NMR) measuring equipment and other instrumental analysis equipment.

The ethylene-α-olefin random copolymer (A) may contain a monomer unit derived from a monomer other than α-olefin as long as it satisfies the above requirement (a). As this monomer, a cyclic olefin, a vinyl aromatic compound (styrene etc.), a polyene compound, etc. are mentioned, for example. The content of the monomer unit is 20 mol % or less, preferably 15 mol % or less, when the total monomer units in the ethylene-α-olefin random copolymer (A) are 100 mol %. In addition, the three-dimensional structure, branching, branching degree distribution, and molecular weight distribution of the ethylene-α-olefin random copolymer (A) are not particularly limited as long as the above-mentioned condition (a) is satisfied. For example, a copolymer having long-chain branching Generally, the mechanical properties are good, and there are also advantages such as increased melt tension (melt tension) during sheet molding and improved calender formability. A copolymer with a narrow molecular weight distribution polymerized using a single-site catalyst has advantages such as less low-molecular-weight components and relatively less blocking of raw material particles.

The melt flow rate (MFR) of the ethylene-α-olefin random copolymer (A) used in the present invention is not particularly limited, and an MFR (JIS K7210, temperature: 190°C, load: 21.18N) of 0.5 is usually used. About ~100g/10min, more preferably 2~50g/10min, more preferably 3~30g/10min ethylene-α-olefin random copolymer. Here, MFR may be selected in consideration of molding processability during sheet molding, adhesiveness during packaging of solar cell elements (batteries), immersion conditions, and the like. For example, when calendering a sheet, MFR is preferably relatively low, specifically about 0.5 to 5 g/10 min, in terms of handling performance when the sheet is peeled off from the forming roll. In molding, from the viewpoint of reducing the extrusion load and increasing the extrusion amount, MFR is preferably used at 2 to 50 g/10 min, more preferably at 3 to 30 g/10 min. Furthermore, from the viewpoint of adhesiveness and ease of immersion when sealing a solar cell element (battery), MFR is preferably 2 to 50 g/10 min, more preferably 3 to 30 g/10 min.

The method for producing the ethylene-α-olefin random copolymer (A) used in the present invention is not particularly limited, and a known polymerization method using a known catalyst for olefin polymerization can be employed. Examples include slurry polymerization and solution polymerization using multi-site catalysts represented by Ziegler-Natta catalysts, single-site catalysts represented by metallocene catalysts, and post-metallocene catalysts. , a bulk polymerization method, a gas phase polymerization method, etc., and a bulk polymerization method using a radical initiator, etc. are also mentioned. In the present invention, since the ethylene-α-olefin random copolymer (A) is a relatively soft resin, it is preferable to use A single-site catalyst polymerization method capable of polymerizing raw materials with few low-molecular-weight components and a narrow molecular weight distribution.

The ethylene-α-olefin random copolymer (A) used in the present invention needs to meet the condition (a) The heat of crystal fusion measured at a heating rate of 10°C/min in differential scanning calorimetry is 0~70J/g , preferably 5~70J/g, more preferably 10~65J/g. If it exists in this range, since the flexibility, transparency (total light transmittance), etc. of the solar cell encapsulating material of this invention will be ensured, it is preferable. In addition, when the heat of crystal fusion is 5 J/g or more, since troubles such as blocking of raw material particles are less likely to occur, it is preferable. Here, as a reference value for the heat of fusion of the crystals, general-purpose high-density polyethylene (HDPE) is about 170 to 220 J/g, and low-density polyethylene resin (LDPE) and linear low-density polyethylene (LLDPE) are 100 J/g. ~160J/g or so.

The heat of fusion of the crystals can be measured at a heating rate of 10° C./min in accordance with JIS K7122 using a differential scanning calorimeter.

In addition, the crystal melting peak temperature of the ethylene-α-olefin random copolymer (A) used in the present invention is not particularly limited, but is usually less than 100°C, and in many cases is 30 to 90°C. Here, as a reference value for the crystal melting peak temperature, general-purpose high-density polyethylene (HDPE) is about 130 to 145°C, and low-density polyethylene resin (LDPE) and linear low-density polyethylene (LLDPE) are 100°C. ~125℃ or so. That is, if the ethylene-α-olefin random copolymer (A) used in the present invention is used alone, it is difficult to achieve a crystal melting peak temperature of 100 °C measured at a heating rate of 10 °C/min in differential scanning calorimetry. Above ℃ and the heat of crystallization fusion is 5~70J/g.

This crystal melting peak temperature can be measured at a heating rate of 10° C./min in accordance with JIS K7121 using a differential scanning calorimeter.

Specific examples of the ethylene-α-olefin random copolymer (A) used in the present invention include the trade names "Engage" and "Affinity" manufactured by Dow Chemical Co., Ltd., and the trade names "Engage" and "Affinity" manufactured by Mitsui Chemicals, Ltd. TAFMER A", "TAFMER P", trade name "Karner" manufactured by Nippon Polyethylene Co., Ltd., etc.

[Ethylene-α-olefin block copolymer (B)]

The ethylene-α-olefin block copolymer (B) used in the present invention is not particularly limited as long as it satisfies the above-mentioned condition (b), and generally, a block of ethylene and an α-olefin having 3 to 20 carbon atoms can be preferably used. copolymer. Here, examples of α-olefins to be copolymerized with ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene. ene, 3-methyl-butene-1, 4-methyl-pentene-1, etc. In the present invention, propylene, 1-butene, 1-hexene, 1-octene, alkene. The α-olefins to be copolymerized with ethylene may be used alone or in combination of two or more.

In addition, the ethylene-α-olefin block copolymer (B) may contain a monomer unit derived from a monomer other than α-olefin as long as it satisfies the above-mentioned condition (b). As this monomer, a cyclic olefin, a vinyl aromatic compound (styrene etc.), a polyene compound, etc. are mentioned, for example. The content of the monomer unit is 20 mol % or less, preferably 15 mol % or less, when the total monomer units in the ethylene-α-olefin block copolymer (B) are 100 mol %.

The block structure of the ethylene-α-olefin block copolymer (B) used in the present invention is not particularly limited as long as it satisfies the above-mentioned condition (b), but the balance of flexibility, heat resistance, transparency, etc. From the viewpoint of comonomer content, crystallinity, density, crystal melting peak temperature (melting point Tm), or glass transition temperature (Tg), it is preferable to contain two or more, preferably three or more segments or Block multi-block structure. Specifically, a completely symmetrical block, an asymmetrical block, a tapered block structure (a structure in which the ratio of the block structure gradually increases in the main chain) and the like are exemplified. Regarding the structure and production method of the copolymer having a multi-block structure, the pamphlets of International Publication No. 2005/090425 (WO2005/090425), International Publication No. 2005/090426 (WO2005/090426), and The structure and manufacturing method are disclosed in detail in International Publication No. 2005/090427 pamphlet (WO2005/090427) and the like.

In the present invention, the ethylene-α-olefin block copolymer having the above multi-block structure will be described in detail below.

An ethylene-α-olefin block copolymer having such a multi-block structure can be preferably used in the present invention, and an ethylene-octene multi-block copolymer containing 1-octene as an α-olefin as a copolymerization component is preferable. As such a block copolymer, a multi-block copolymer in which an almost amorphous soft segment obtained by copolymerizing a large amount of octene with respect to ethylene (approximately 15 to 20 mol %) and octene with respect to ethylene is preferable. Two or more highly crystalline hard segments each having a crystal melting peak temperature of 110 to 145° C. obtained by copolymerization in a small amount (approximately less than 2 mol %) exist. Both flexibility and heat resistance can be achieved by controlling the chain lengths and ratios of these soft segments and hard segments.

As a specific example of the copolymer which has this multi-block structure, the brand name "Infuse" by Dow Chemical company is mentioned.

The melt flow rate (MFR) of the ethylene-α-olefin block copolymer (B) used in the present invention is not particularly limited, but generally used MFR (JIS K7210, temperature: 190°C, load: 21.18N) is An ethylene-α-olefin block copolymer of about 0.5 to 100 g/10 min, more preferably 1 to 50 g/10 min, further preferably 1 to 30 g/10 min, and particularly preferably 1 to 10 g/10 min.

Here, MFR may be selected in consideration of molding processability during sheet molding, adhesiveness during encapsulation of solar cell elements (batteries), immersion conditions, and the like. Specifically, when calendering a sheet, MFR is preferably relatively low, specifically about 0.5 to 5 g/10 min, from the viewpoint of handling performance when peeling the sheet from a forming roll. In extrusion molding, it is preferable to use MFR of 1 to 30 g/10 min from the viewpoint of reducing the extrusion load and increasing the extrusion amount. Furthermore, from the viewpoint of adhesiveness and easiness of immersion when encapsulating a solar cell element (battery), an MFR of 3 to 50 g/10 min is preferably used.

The ethylene-α-olefin block copolymer (B) used in the present invention needs to satisfy the condition (b) that the crystal melting peak temperature measured at a heating rate of 10°C/min in differential scanning calorimetry is 100°C or higher, And the heat of crystallization fusion is 5~70J/g. The crystal melting peak temperature is preferably 105°C or higher, more preferably 110°C or higher, and the upper limit is usually 145°C. In addition, the heat of crystal fusion is preferably 10 to 60 J/g, more preferably 15 to 55 J/g. The methods for measuring the crystal melting peak temperature and the crystal melting heat are as described above.

Generally, solar cell modules are heated up to about 85-90°C due to heat generation during power generation, radiant heat from sunlight, etc., but if the crystal melting peak temperature is above 100°C, the durability of the solar cell encapsulation material of the present invention can be ensured. It is thermal, so it is preferable. On the other hand, if the upper limit temperature is 145° C., it is preferable because the sealing can be performed without excessively high temperature in the sealing step of the solar cell element. In addition, if the heat of crystal fusion is within this range, the flexibility, transparency (total light transmittance), etc. of the solar cell encapsulating material of the present invention are ensured, and in addition, problems such as sticking of raw material particles are also difficult to occur, so it is preferable .

[Resin composition (C)]

The layer (II) in the present invention is composed of a resin composition (C) containing the above-mentioned ethylene-α-olefin random copolymer (A) and ethylene-α-olefin block copolymer (B). Here, the types of α-olefins used in these copolymers (A) and copolymers (B) may be the same or different. In the present invention, if they are the same, the compatibility at the time of mixing will be improved, and solar cell encapsulation will be improved. The transparency of the material, that is, improves the photoelectric conversion efficiency of the solar cell, and is therefore preferable.

Furthermore, from the viewpoint of the ease of regeneration and addition during the production of the solar cell encapsulating material of the present invention, the improvement of economical efficiency such as yield due to this, and the maintenance of transparency of the (II) layer when regeneration and addition are performed Starting from the above, when the (I) layer is composed of the resin composition (Z), the types of α-olefins used in the above-mentioned polyethylene-based resin (X) and the above-mentioned silane-modified vinyl-based resin (Y) are different from those in (II) It is preferable that the types of α-olefins respectively used in the above-mentioned copolymer (A) and the above-mentioned copolymer (B) of the layer are all the same.

Next, the ethylene-α-olefin random copolymer (A) in the resin composition (C) is block-copolymerized with ethylene-α-olefin from the viewpoint of excellent balance of flexibility, heat resistance, and transparency. The content of the substance (B) is preferably 50 to 99 parts by mass, 1 to 50 parts by mass, more preferably 60 to 98 parts by mass, and 2 to 40 parts by mass when the resin composition (C) is 100 parts by mass. , More preferably 70~97 parts by mass, 3~30 parts by mass. In addition, the mixing (containing) mass ratio of the ethylene-α-olefin random copolymer (A) to the ethylene-α-olefin block copolymer (B) is not particularly limited, but is preferably (A)/(B)= 99~50/1~50, more preferably 98~60/2~40, more preferably 97~70/3~30, more preferably 97~80/3~20, more preferably 97~90/3~ 10. However, the total of the ethylene-α-olefin random copolymer (A) and the ethylene-α-olefin block copolymer (B) is 100 parts by mass. Here, when the mixing (containing) mass ratio is within this range, it is easy to obtain a solar cell encapsulating material with an excellent balance of flexibility, heat resistance, transparency, and the like, which is preferable.

In the resin composition (C) constituting the (II) layer, various physical properties (flexibility, heat resistance, transparency, adhesiveness, etc.), molding process For the purpose of improving performance or economy, resins other than the above-mentioned ethylene-α-olefin random copolymer (A) and ethylene-α-olefin block copolymer (B) may be mixed. Examples of the resins other than (A) and (B) include the polyolefin-based resin used in the (I) layer and the same resins as other resins. When mixing resins other than ethylene-α-olefin random copolymer (A) and ethylene-α-olefin block copolymer (B), usually when the resin composition (C) is 100 parts by mass , preferably 20 parts by mass or less, more preferably 10 parts by mass or less.

In addition, various additives may be added to the layer (I) and the layer (II) as necessary. Examples of such additives include antioxidants, ultraviolet absorbers, weather stabilizers, light diffusing agents, nucleating agents, pigments (for example, white pigments), flame retardants, anti-discoloration agents and the like. In the present invention, it is preferable to add at least one additive selected from antioxidants, ultraviolet absorbers, and weather-resistant stabilizers for reasons described later. In addition, in the present invention, a crosslinking agent and a crosslinking auxiliary agent may be added to the resin composition (C). For example, when high heat resistance is required, a crosslinking agent and/or a crosslinking auxiliary agent may be added. agent. In the present invention, in the present invention, it is preferable to add an antioxidant, an ultraviolet absorber, or a weather-resistant stabilizer.

Various types of antioxidants such as monophenol-based, bisphenol-based, high-molecular-weight phenol-based, sulfur-based, and phosphite-based antioxidants can be used as the antioxidant. Examples of monophenols include 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol and the like. Examples of bisphenols include 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis-(4-ethyl- 6-tert-butylphenol), 4,4′-thiobis-(3-methyl-6-tert-butylphenol), 4,4′-butylidene-bis-(3-methyl-6- tert-butylphenol), 3,9-bis[{1,1-dimethyl-2-{β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl Base} 2,4,9,10-tetraoxaspiro] 5,5-undecane, etc.

Examples of polymeric phenols include 1,1,3-tris-(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2, 4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetrakis-{methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl ) propionate} methane, bis{(3,3′-bis-4′-hydroxy-3′-tert-butylphenyl)butanoic acid}diol ester, 1,3,5-tri(3′,5 '-di-tert-butyl-4'-hydroxybenzyl)-s-triazine-2,4,6-(1H,3H,5H)trione, triphenol (vitamin E), etc.

Examples of sulfur-based compounds include dilauryl thiodipropionate, dimyristyl thiodipropionate, distearyl thiopropionate, and the like.

Examples of phosphite esters include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, 4,4'-butylidene-bis(3-methyl-6 -tert-butylphenyl-di-tridecyl)phosphite, cycloneopentanetetraylbis(octadecylphosphite), tri(mono and/or di)phenylphosphite, di Isodecylpentaerythritol diphosphite, 9,10-dihydro-9-oxa-10-phosphinophenanthrene-10-oxide, 10-(3,5-di-tert-butyl-4-hydroxybenzyl)- 9,10-dihydro-9-oxa-10-phosphinephenanthrene-10-oxide, 10-decyloxy-9,10-dihydro-9-oxa-10-phosphinephenanthrene, cycloneopentane tetra Bis(2,4-di-tert-butylphenyl)phosphite, cycloneopentanetetraylbis(2,6-di-tert-methylphenyl)phosphite, 2,2-methylenebis (4,6-tert-butylphenyl) octyl phosphite, etc.

In the present invention, from the viewpoint of the effect of the antioxidant, thermal stability, economy, etc., phenolic and phosphate-based antioxidants can be preferably used, and both are more preferably used in combination. The addition amount of this antioxidant is about 0.1-1 mass part normally with respect to 100 mass parts of resin compositions which comprise each (I) layer and (II) layer, Preferably it adds 0.2-0.5 mass part.

Various types of ultraviolet absorbers such as benzophenone-based, benzotriazole-based, triazine-based, and salicylate-based ultraviolet absorbers can be used as the ultraviolet absorber. Examples of benzophenone-based ultraviolet absorbers include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2- Hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-n-octadecyloxybenzophenone, 2-hydroxy- 4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2,4-dihydroxydiphenyl Methanone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4, 4'-Tetrahydroxybenzophenone, etc.

The benzotriazole-based ultraviolet absorber is a hydroxyphenyl-substituted benzotriazole compound, for example, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2- Hydroxy-5-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-dimethylphenyl)benzotriazole, 2-(2-methyl-4-hydroxyphenyl ) benzotriazole, 2-(2-hydroxy-3-methyl-5-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-amylphenyl) Benzotriazole, 2-(2-hydroxy-3,5-di-tert-butylphenyl)benzotriazole and the like. In addition, examples of triazine-based ultraviolet absorbers include 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-( octyloxy)phenol, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-(hexyloxy)phenol, etc. Examples of salicylate esters include phenyl salicylate, p-octylphenyl salicylate, and the like.

The amount of the ultraviolet absorber to be added is usually not less than 0.01 parts by mass, preferably not less than 0.05 parts by mass and preferably not more than 2.0 parts by mass, based on 100 parts by mass of the resin composition constituting each of the (I) layer and (II) layer, It is preferable to add in the range of 0.5 mass part or less.

A hindered amine-based light stabilizer can be preferably used as a weather-resistant stabilizer that imparts weather resistance in addition to the above ultraviolet absorber. A hindered amine-based light stabilizer does not absorb ultraviolet rays like ultraviolet absorbers, but shows a remarkable synergistic effect when used in combination with ultraviolet absorbers. There are light stabilizers that function as light stabilizers other than hindered amines, but they are often colored, so they are not preferable for the layer (I) in the present invention.

As the hindered amine light stabilizer, dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, poly[ {6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl- 4-piperidinyl)imino}hexamethylene{{2,2,6,6-tetramethyl-4-piperidinyl}imino}], N,N'-bis(3-aminopropyl ) Ethylenediamine-2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidinyl)amino]-6-chloro-1,3 , 5-triazine condensate, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 2-(3,5-di-tert-4-hydroxybenzyl) -2-n-butylmalonate bis(1,2,2,6,6-pentamethyl-4-piperidinyl), etc. The added amount of the hindered amine light stabilizer is usually 0.01 mass part or more, preferably 0.05 mass part or more, and preferably 0.5 mass parts with respect to 100 mass parts of the resin composition constituting each (I) layer and (II) layer. It is added in a range of not more than 0.3 parts by mass, preferably not more than 0.3 parts by mass.

The above-mentioned antioxidant, ultraviolet absorber, and weather-resistant stabilizer may be used alone or in combination of two or more, and an ultraviolet absorber and weather-resistant stabilizer may be used in combination. In general, yellowing tends to be caused more easily as their addition amount becomes larger, so it is preferable to stop adding the minimum amount required.

The thickness of the (II) layer constituting the solar cell encapsulating material of the present invention is not particularly limited, but from the viewpoint of cushioning against impacts to the solar cell module, etc., encapsulation against the uneven surface of the cell, insulation, transparency, etc., Usually 0.02 mm or more, preferably 0.04 mm or more, more preferably 0.1 mm or more, more preferably 0.15 mm or more, and about 1 mm or less, preferably 0.8 mm or less, more preferably 0.6 mm or less, even more preferably 0.5 mm The following will do.

<Solar cell encapsulation material>

The solar cell encapsulating material of the present invention needs to have at least the above (I) layer and the above (II) layer. The layer configuration is not particularly limited as long as it has at least one (I) layer and (II) layer, and examples include two types of two-layer configurations such as (I) layer/(II) layer, (I) layer A three-layer structure composed of two types of layers such as /(II) layer/(I) layer, a two-type four-layer structure such as (I) layer/(II) layer/(I) layer/(II) layer, etc.

Among them, in the present invention, from the viewpoint of improving the adhesion with the front sheet, the back sheet, and the solar cell element, it is preferable to have (I) layer on at least one of the outermost layers, and it is more preferable to include Both sides have (I) layer.

The film-making method of the solar cell encapsulation material in the present invention can adopt known method, for example can adopt the melt mixing equipment with single-screw extruder, multi-screw extruder, Banbury internal mixer, kneader etc. and use The extrusion casting method, calendering method, etc. of the T-die are not particularly limited, but in the present invention, a co-extrusion method using a plurality of extruders is preferably employed from the viewpoint of operability, productivity, and the like.

The molding temperature in the co-extrusion method using a T-die can be appropriately adjusted according to the flow characteristics and film-forming properties of the resin composition used, and is approximately 80°C or higher, preferably 100°C or higher, and more preferably 120°C Above, more preferably 140°C or more, and 300°C or less, preferably 250°C or less, more preferably 200°C or less, still more preferably 180°C or less, in the case of adding a radical initiator, a silane coupling agent, etc. , in order to suppress the increase in resin pressure and the increase in fish eyes accompanying the crosslinking reaction, it is preferable to lower the molding temperature. Various additives such as free radical initiators, silane coupling agents, antioxidants, UV absorbers, weather stabilizers, light diffusing agents, nucleating agents, pigments (such as white pigments), flame retardants, and anti-tarnish agents can be pre-mixed with The resins are dry-blended together and supplied to a hopper, or all the materials may be melt-mixed in advance to form pellets and supplied, or a masterbatch in which only the additives are pre-concentrated in the resin may be produced and supplied.

On the surface of the solar cell encapsulating material of the present invention obtained in the form of a sheet, if necessary, in order to prevent the adhesion of the sheets when the sheet is made into a roll, to improve the handling performance in the solar cell element encapsulation process, and to facilitate degassing Embossing and various concave and convex (conical, square cone, hemispherical, etc.) processing can be performed for purposes such as durability.

Moreover, surface treatment, such as a corona treatment and a plasma treatment, can be given to at least one surface of the solar cell encapsulating material of this invention from a viewpoint of improving adhesiveness.

Furthermore, for the purpose of improving the handleability of the sheet when forming a film, etc., it can be used with another base film (stretched polyester film (OPET), stretched polypropylene film (OPP), etc.) Lamination, sandwich lamination and other methods for lamination.

The flexibility of the solar cell encapsulating material of the present invention may be appropriately adjusted in consideration of the shape, thickness, installation location, etc. of the solar cell to be applied. The storage modulus (E') of ℃ is 1~2000MPa. From the viewpoint of protecting the solar cell element, the storage elastic modulus (E') is preferably lower, but in consideration of handling properties such as sheet shape, prevention of adhesion between sheet surfaces, etc., it is more preferably 3 to 1000 MPa , more preferably 5~500MPa, particularly preferably 10~100MPa. If the lower limit of the storage modulus (E') is the above value, it is preferable for the rigidity of the solar cell module support, and if the upper limit of the storage modulus (E') is the above value, since the The impact of the battery pack and the like is good, so the battery protection is good.

The storage elastic modulus (E′) can be measured at a predetermined temperature at a vibration frequency of 10 Hz using a viscoelasticity measuring device, and a value at a temperature of 20° C. can be obtained.

The total light transmittance of the solar cell encapsulation material of the present invention is sometimes not high when the applied solar cell type is, for example, amorphous thin-film silicon type, etc., and is applied to a position where sunlight is not blocked and reaches solar electronic components Considering the photoelectric conversion efficiency of the solar cell and the handling performance when overlapping various components, etc., it is preferably 85% or more, more preferably 87% or more, and even more preferably 90% or more.

The total light transmittance and haze can be obtained by measuring with a haze meter in accordance with JIS K7361.

The heat resistance of the solar cell encapsulating material of the present invention is determined by the properties of the resin composition constituting the (I) layer (crystal melting peak temperature, crystal melting heat, MFR, molecular weight, etc.), the ethylene-α - Various properties of olefin random copolymer (A) (crystal melting peak temperature, crystal melting heat, MFR, molecular weight, etc.) and ethylene-α-olefin block copolymer (B) properties (crystal melting peak temperature, crystallization heat of fusion, MFR, molecular weight, etc.), but the crystalline melting peak temperature of the ethylene-α-olefin block copolymer (B) is particularly strongly affected. In general, solar cell modules are heated to about 85 to 90°C due to heat generation during power generation, radiant heat from sunlight, etc., but if the crystal melting peak temperature is 100°C or higher, the solar cell encapsulation material of the present invention can be guaranteed. Heat resistance is therefore preferred.

In the present invention, the heat resistance can be evaluated, for example, by making a sample obtained by stacking a sheet-shaped sealing material between a white plate glass and an aluminum plate, laminating and pressing it at a predetermined temperature with a vacuum press, and heating the sample at 100°C. The constant temperature bath is set to incline to a specified angle, and the state after a specified time is observed for evaluation.

The flexibility, heat resistance, and transparency of the solar cell encapsulating material of the present invention tend to be incompatible characteristics. Specifically, if the crystallinity of the resin composition (C) used in the layer (II) to improve flexibility is too low, the heat resistance will fall and become insufficient. On the other hand, if the crystallinity of the resin composition (C) used in the (II) layer for improving heat resistance is increased too much, the transparency will fall and become insufficient.

In the present invention, for their balance, the storage modulus (E') at a vibration frequency of 10 Hz and a temperature of 20°C in the measurement of dynamic viscoelasticity is used as an index of flexibility, and an ethylene-α-olefin block copolymer (B ) in the differential scanning calorimetry measurement at a heating rate of 10 ° C / min peak crystal melting temperature as the heat resistance index, and the total light transmittance is used as the transparency index, the three indexes are preferably stored The energy modulus (E') is 1~2000MPa, the crystallization melting peak temperature is above 100°C, the total light transmittance is above 85%, and the storage elastic modulus (E') is further preferably 5~500MPa, and the crystallization melting peak temperature is 105~145°C, the total light transmittance is above 85%, especially preferably the storage modulus (E') is 10~100MPa, the crystal melting peak temperature is 110~145°C, and the total light transmittance is above 90%.

The solar cell encapsulating material of the present invention is excellent in adhesiveness and long-term stability of adhesive force. As described above, in the conventional method of adding a silane coupling agent to impart an adhesive force, there is a possibility that the silane coupling agent oozes out over time and reacts with moisture to lower the adhesive force. On the other hand, since the encapsulating material of the present invention has at least the layer (I) that exhibits excellent adhesion without using a silane coupling agent and does not need to worry about bleeding of additives, it is an excellent combination of adhesiveness and adhesiveness. Encapsulation material with excellent long-term stability.

These properties can be adjusted appropriately in consideration of the shape, thickness, installation location, etc. of the solar cell to be applied. Between the glass and a 0.16 mm thick fluorine-based backsheet (manufactured by KREMPEL, trade name: AKASOL), a sheet-shaped packaging material with a thickness of 0.45 mm and a PET film with a thickness of 0.012 mm, a length of 50 mm, and a width of 30 mm (Mitsubishi Plastics Co., Ltd. manufactured, trade name: Diafoil), make a starting point between the glass and the packaging material, and use a vacuum press to carry out lamination and pressing under the conditions of 150°C and 15 minutes. The adhesive force when evaluating the adhesiveness under the condition of 50 mm/sec is preferably 10 N/15 mm width or more, more preferably 15 N/15 mm width or more, still more preferably 20 N/15 mm width or more.

In addition, with regard to the long-term stability of the adhesive force, after the packaging material of the present invention is formed into a film and left for 4 months at 25° C. and 50% RH, the adhesive force when the aforementioned adhesive force is implemented is preferably 10N/15mm width or more, more preferably 15N/15mm width or more, still more preferably 20N/15mm width or more.

The thickness ratio of the (I) layer and (II) layer in the solar cell encapsulating material of the present invention is not particularly limited, but from the viewpoint of adhesiveness and transparency, (I)/(II) is preferably 50/50~ 10/90, more preferably 40/60 to 10/90.

The total thickness of the solar cell encapsulating material of the present invention is not particularly limited, but is usually 0.02 mm or more, preferably 0.02 mm or more, from the viewpoint of cushioning properties against impacts such as solar cell modules, sealing properties against the uneven surface of the battery, and insulating properties. 0.04 mm or more, more preferably 0.1 mm or more, more preferably 0.15 mm or more, still more preferably 0.2 mm or more, and about 1 mm or less, preferably 0.8 mm or less, more preferably 0.6 mm or less, still more preferably 0.5 mm or less .

<solar cell module>

A solar cell module can be manufactured by using the solar cell encapsulating material of the present invention and fixing a solar cell element with glass as upper and lower protective materials, or a front sheet and a back sheet. As such a solar cell module, various types of modules can be exemplified, and preferably, a solar cell module manufactured using the solar cell encapsulating material, the upper protective material, the solar cell element, and the lower protective material of the present invention, Concretely, it can be enumerated that the upper protective material/encapsulating material (encapsulating resin layer) of the present invention/solar cell element/encapsulating material (encapsulating resin layer) of the present invention/lower protective material is obtained from the solar cell element. The two sides are sandwiched by the encapsulation material of the present invention (see FIG. 1), the encapsulation material of the present invention and the upper protective material are formed on the solar cell element formed on the inner peripheral surface of the lower protective material, and the upper protective material is formed on the upper part. The solar cell element on the inner peripheral surface of the protective material, for example, the structure in which the lower protective material of the encapsulation material of the present invention is formed on the element obtained by sputtering or the like on a fluororesin-based transparent protective material to form an amorphous solar cell element wait. It should be noted that in the solar cell module using the solar cell encapsulating material of the present invention, when the encapsulating material is used in two or more positions, the solar cell encapsulating material of the present invention may be used in all positions, or only The solar cell encapsulating material of the present invention is used at one site. In addition, when the encapsulating material is used in two or more places, the resin composition constituting the solar cell encapsulating material of the present invention used in each place may be the same or different.

The solar cell elements are arranged and wired between encapsulating resin layers. Examples include III-V and II-VI compound semiconductor types such as monocrystalline silicon type, polycrystalline silicon type, amorphous silicon type, gallium-arsenic, copper-indium-selenium, and cadmium-tellurium, dye-sensitized type, Organic film type, etc.

The components constituting the solar cell module produced using the solar cell encapsulating material of the present invention are not particularly limited, but examples of upper protective materials include glass, acrylic resin, polycarbonate, polyester, and fluororesin Single-layer or multi-layer protective materials such as plates and films. The lower protective material is a single-layer or multi-layer sheet of metal, various thermoplastic resin films, etc., for example, metals such as tin, aluminum, stainless steel, inorganic materials such as glass, polyester, and those with deposited inorganic substances. Single-layer or multi-layer protective materials of polyester, fluororesin, polyolefin, etc.

The surfaces of these upper and lower protective materials may be subjected to known surface treatments such as plasma treatment and corona treatment in order to improve adhesion with the solar cell encapsulating material of the present invention and other members.

For the solar cell assembly made by using the solar cell encapsulation material of the present invention, use the encapsulation material to sandwich the solar cell element from both sides in the above-mentioned manner according to the upper protection material/encapsulation material/solar cell element/encapsulation material/lower protection material. The structure of the support is described as an example. As shown in the figure, a transparent substrate 10, an encapsulating resin layer 12A using the solar cell encapsulating material of the present invention, solar cell elements 14A, 14B, and a package using the solar cell encapsulating material of the present invention are sequentially stacked from the sunlight light receiving side. Resin layer 12B, back sheet 16 , and junction box 18 (terminal box for connecting wiring for taking out electricity generated from the solar cell element to the outside) are bonded to the lower surface of back sheet 16 . The solar cell elements 14A and 14B are connected by wiring 20 in order to lead the generated current to the outside. The wiring 20 is taken out to the outside through a through hole (not shown) provided in the back plate 16 and connected to the junction box 18 .

As a method of manufacturing a solar cell module, a known method can be applied, and it is not particularly limited. Generally, there are steps of sequentially laminating an upper protective material, an encapsulating resin layer, a solar cell element, an encapsulating resin layer, and a lower protective material. They carry out the process of vacuum suction and heating and pressing. In addition, batch type manufacturing equipment, roll-to-roll type manufacturing equipment, etc. can also be applied.

The solar cell module made by using the solar cell encapsulation material of the present invention can be applied to small solar cells represented by mobile machines no matter indoors or outdoors according to the type of solar cells to be applied and the shape of the module. Various uses such as large solar cells on roofs and roof decks.

Example

Hereinafter, the present invention will be described in further detail through examples, but the present invention is not limited thereto.

<Evaluation>

Various measurements and evaluations of the sealing material sheet in this example were performed as follows.

(Crystal melting peak temperature (Tm))

Using a differential scanning calorimeter (trade name "Pyrls1DSC" manufactured by Perkinelmer Co., Ltd.), according to JIS K7121, a sample of about 10 mg was heated from -40°C to 200°C at a heating rate of 10°C/min. After keeping at ℃ for 5 minutes, cool down to -40℃ at a cooling rate of 10℃/min, and then heat up to 200℃ at a heating rate of 10℃/min, measure the thermogram, and obtain the crystallization from the thermogram Melting peak temperature (Tm) (°C).

(Crystal fusion heat (ΔHm))

Using a differential scanning calorimeter (trade name "Pyrls1DSC" manufactured by Perkinelmer Co., Ltd.), according to JIS K7122, a sample of about 10 mg was heated from -40°C to 200°C at a heating rate of 10°C/min. After keeping it for 5 minutes, the temperature was lowered to -40°C at a cooling rate of 10°C/min, and again, when the temperature was raised to 200°C at a heating rate of 10°C/min, the thermogram was measured, and the crystal melting rate was obtained from the thermogram. Heat (ΔHm) (J/g).

(adhesiveness)

(1) Tablets of Examples 1-4 and Comparative Examples 1-3

Regarding the adhesion to glass, whiteboard glass with a thickness of 2 mm, a length of 150 mm, and a width of 25 mm and a fluorine-based back sheet with a thickness of 0.16 mm (manufactured by KREMPEL, trade name: AKASOL, with an easy-adhesive coating layer, PVF/PET /PVF laminate) A sheet-shaped encapsulating material with a thickness of 0.45 mm and a PET film (manufactured by Mitsubishi Plastics Corporation, trade name: Diafoil) with a thickness of 0.012 mm, 50 mm in length, and 30 mm in width are stacked between the glass and the encapsulating material At the beginning of the production, use a vacuum press machine to perform lamination and pressing at a temperature of 150°C for 10 minutes. After preparing a sample, the glass is clamped in the grip of a tensile testing machine (manufactured by INTESCO, trade name: 200X testing machine). The chuck, and the back sheet and the sealing material were mounted on the other chuck, and the adhesiveness was evaluated under the conditions of an angle of 180 degrees and a tensile speed of 50 mm/sec, and the evaluation was performed according to the following criteria.

(○) Adhesive strength of 10N/15mm width or more

(×) Adhesive strength less than 10N/15mm wide

(2) Tablets of Examples 6-9 and Comparative Example 4

Embossed whiteboard glass (manufactured by Asahi Glass Co., Ltd., trade name: Solite) with a thickness of 3.2 mm, length 150 mm, and width 150 mm, and a fluorine-based back sheet (manufactured by Krempel, trade name: ACASOL) with a thickness of 0.33 mm have easy adhesion. A PET film (manufactured by Mitsubishi Plastics Corporation, trade name: Diafoil) with a thickness of 0.012 mm, a length of 90 mm, and a width of 150 mm and a sheet-shaped sealing material with a thickness of 0.45 mm were laminated between the coating layer, PVF/PET/PVF laminate, The starting point is made of a PET film between the glass and the sealing material, and laminated at a temperature of 150°C, vacuum for 3 minutes, and pressing for 7 minutes with a vacuum laminator (manufactured by Nisshinbo Co., Ltd., trade name: PVL0505S). After sampling, a test piece with a width of 10mm was prepared, and the glass was clamped by the chuck of a tensile testing machine (manufactured by INTESCO, trade name: 200X), and the backplane and sealing material were mounted on the other chuck, and the Adhesiveness was evaluated under conditions of an angle of 180 degrees and a tensile speed of 50 mm/min, and was evaluated according to the following criteria.

(◎) Adhesive strength of 100N/15mm width or more

(○) Adhesive force is more than 20N/15mm wide and less than 100N/15mm wide

(×) The adhesive force is less than 20N/15mm wide

(3) Tablets of Examples 11 and 12

Using a corona treatment machine with an irradiation width of 0.5m, under the conditions of irradiation intensity: 300W and irradiation speed: 10m/min (corona treatment capacity: 60W·min/m ² ), the packaging material is corona treated. Embossed whiteboard glass (manufactured by Asahi Glass Co., Ltd., trade name: Solite) with a thickness of 3.2 mm, length 150 mm, and width 150 mm and a fluorine-based backsheet (manufactured by Cybrid Co., Ltd., wetting index: 42 mN/m) with a thickness of 0.33 mm, without Easy-adhesive layer, PVdF/PET/PVdF laminate) A PET film (manufactured by Mitsubishi Plastics Corporation, trade name: Diafoil) with a thickness of 0.012 mm, a length of 90 mm, and a width of 150 mm and a corona-treated film with a thickness of 0.45 mm sheet-shaped packaging material, the starting point is made of PET film between the glass and the packaging material, using a vacuum laminator (manufactured by Nisshinbo Co., Ltd., trade name: PVL0505S), at a temperature of 150 ° C, vacuum for 3 minutes, and press for 7 minutes Laminate under the condition of lamination, after preparing the sample, make a test piece with a width of 10mm, clamp the glass on the chuck of the tensile testing machine (manufactured by INTESCO, trade name: 200X), and then install the backplane and the sealing material on another For one chuck, the adhesiveness was evaluated under the conditions of an angle of 180 degrees and a tensile speed of 50 mm/min.

(adhesion long-term stability)

After forming films of various sealing materials and exposing them for 4 months under the conditions of a temperature of 25°C and a humidity of 50%, samples were produced in the same manner as the above adhesive evaluation, and the adhesiveness was evaluated according to the following criteria.

(○) Adhesive strength of 10N/15mm width or more

(×) Adhesive strength less than 10N/15mm wide

(transparency; total light transmission)

(1) Tablets of Examples 1-4 and Comparative Examples 1-3

A sheet-shaped packaging material with a thickness of 0.45 mm is stacked between two sheets of white glass (manufactured by SCHOTT Co., Ltd., trade name: B270, size: 50 mm in length and 50 mm in width) with a thickness of 2 mm, and heated at 150°C for 1 minute using a hot press machine Press under the conditions to make a sample, measure the total light transmittance according to JIS K7105, and record the value, and also record the results of evaluation according to the following criteria.

(◎) The total light transmittance is above 90%

(○) The total light transmittance is more than 85% and less than 90%

(×) The total light transmittance is less than 85% or it is obviously cloudy (not determined)

(2) Tablets of Examples 6-9 and Comparative Example 4

A sheet-shaped packaging material with a thickness of 0.45 mm was laminated between two sheets of white plate glass (manufactured by SCHOTT Co., Ltd., trade name: B270, size: 50 mm in length and 50 mm in width) with a thickness of 2 mm, and the same vacuum laminator as above was used. Laminate pressing was carried out at a temperature of 150°C, vacuum for 5 minutes, and pressing for 30 seconds. After making a sample, measure it with a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., trade name: NDH-5000) in accordance with JIS K7361. For the total light transmittance, the value is described, and the results of evaluation according to the following criteria are also described together.

(○) The total light transmittance is above 85%

(×) The total light transmittance is less than 85% or it is obviously cloudy (not determined)

(transparency; haze)

Samples were produced in the same manner as in the evaluation of the above-mentioned total light transmittance, and the haze was measured using a haze meter according to JIS K7361, and the values were described, and the results of evaluation according to the following criteria were also described.

(○) Haze less than 10%

(×) When the haze is 10% or more or is obviously cloudy (not measured)

(heat resistance)

The overlapping thickness between the 2mm-thick white board glass (dimensions: 75mm in length, 25mm in width) and the aluminum plate (dimensions: 120mm in length, 60mm in width) with a thickness of 5mm is 0.5mm (0.45 in Examples 6 to 9 and Comparative Example 4). mm) sheet-shaped packaging materials, using a vacuum press machine, laminated and pressed at 150°C for 15 minutes (10 minutes in Examples 6-9 and Comparative Example 4), prepared samples, and fixed them on whiteboard glass A heavy stone made of SUS (dimensions: 75mm in length, 25mm in width, weight: about 32g), set the sample at a temperature of 100°C at an inclination of 60 degrees, and observe the state after 500 hours, according to the following criteria evaluate.

(○) The glass does not deviate from the initial reference position

(×) The glass deviates from the initial reference position, or the sheet melts

(average refractive index)

The measurement was performed at a temperature of 23° C. using an Abbe refractometer manufactured by Atago Co., Ltd. in accordance with JIS K7142, using sodium D rays (589 nm) as a light source. Table 2 shows the absolute value of the average refractive index difference between the polyethylene-based resin (X) and the silane-modified vinyl-based resin (Y) in the (I) layer. In addition, as a reference value, the absolute value of the difference of the average refractive index of polyethylene-type resin (X) and another silane-modified vinyl-type resin (W) is shown in the parenthesis of Table 2.

<Constituent material>

The constituent materials used in Examples and Comparative Examples are shown below.

(I) As materials constituting the layers, the following materials were used.

[Polyethylene resin (X)]

(X-1): Ethylene-octene random copolymer (manufactured by Dow Chemical, trade name: Engage8200, ethylene/1-octene=69/31 mass % (89/10 mol %), MFR: 5, Tm : 65℃, ΔHm: 53J/g)

(X-2): Ethylene-octene block copolymer (manufactured by Dow Chemical Co., trade name: Infuse9000, density: 0.875 g/cm ³ , ethylene/1-octene=65/35% by mass (88/12 mol %), crystal melting peak temperature: 122°C, crystal melting heat: 44J/g, storage modulus (E') at 20°C: 27MPa, average refractive index: 1.4899, MFR (temperature: 190°C, load: 21.18N): 0.5g/10min)

(X-3): Ethylene-octene random copolymer (manufactured by Dow Chemical, trade name: AffinityEG8200G, density: 0.870 g/cm ³ , ethylene/1-octene=68/32% by mass (89/11 mol %), crystal melting peak temperature: 59°C, crystal melting heat: 49J/g, storage modulus (E') at 20°C: 14MPa, average refractive index: 1.4856, MFR (temperature: 190°C, load: 21.18N): 5g/10min)

[Silane modified vinyl resin (Y)]

(Y-1): Silane-modified ethylene-octene random copolymer (manufactured by Mitsubishi Chemical Corporation, trade name: LinklonSL800N, density: 0.868g/cm ³ , crystal melting peak temperature: 54°C and 116°C, crystal melting Heat: 22J/g and 4J/g, storage modulus (E') at 20°C: 15MPa, average refractive index: 1.4857, MFR (temperature: 190°C, load: 21.18N): 1.7g/10min)

[Other silane-modified vinyl resins]

(W-1): Silane-modified ethylene-hexene random copolymer (manufactured by Mitsubishi Chemical Corporation, trade name: LinklonXLE815N, density: 0.915 g/cm ³ , crystal melting peak temperature: 121°C, crystal melting heat: 127J /g, storage modulus (E') at 20°C: 398MPa, average refractive index: 1.5056, MFR (temperature: 190°C, load: 21.18N): 0.5g/10min)

As materials constituting the (II) layer, the following materials were used.

[Ethylene-α-olefin random copolymer (A)]

(A-1): Ethylene-octene random copolymer (manufactured by Dow Chemical, trade name: Engage8200, ethylene/1-octene=69/31 mass % (89/10 mol %), MFR: 5, Tm : 65℃, ΔHm: 53J/g)

(A-2): Ethylene-propylene-hexene ternary random copolymer (manufactured by Nippon Polyethylene Co., Ltd., trade name: Karner KJ640T, ethylene/propylene/hexene=80/10/10% by mass (88.2/7.4/ 4.4 mol%), crystal melting peak temperature: 53°C, crystal melting heat: 58J/g, storage modulus (E') at 20°C: 30MPa, average refractive index: 1.4947, MFR (temperature: 190°C, Load: 21.18N): 5g/10min)

(A-3): Ethylene-octene random copolymer (manufactured by Dow Chemical, trade name: AffinityEG8200G, density: 0.870 g/cm ³ , ethylene/1-octene=68/32% by mass (89/11 mol %), crystal melting peak temperature: 59°C, crystal melting heat: 49J/g, storage modulus (E') at 20°C: 14MPa, average refractive index: 1.4856, MFR (temperature: 190°C, load: 21.18N): 5g/10min)

[Ethylene-α-olefin block copolymer (B)]

(B-1): Ethylene-octene block copolymer (manufactured by Dow Chemical, trade name: D9100.05, ethylene/1-octene=63/37 mass % (87.2/12.8 mol %), crystal melting peak Temperature: 119°C, crystal melting heat: 38J/g, MFR (temperature: 190°C, load: 21.18N): 1g/10min)

(B-2): Ethylene-octene block copolymer (manufactured by Dow Chemical, trade name: Infuse9507, density: 0.866 g/cm ³ , ethylene/octene=56/44 mass % (83.6/16.4 mol %) , crystal melting peak temperature: 123°C, crystal melting heat: 21J/g, storage modulus (E') at 20°C: 12MPa, average refractive index: 1.4828, MFR (temperature: 190°C, load: 21.18N ): 5g/10min)

(B-3): Ethylene-octene block copolymer (manufactured by Dow Chemical, trade name: Infuse9000, density: 0.875 g/cm ³ , ethylene/1-octene=65/35% by mass (88/12 mol %), crystal melting peak temperature: 122°C, crystal melting heat: 44J/g, storage modulus (E') at 20°C: 27MPa, average refractive index: 1.4899, MFR (temperature: 190°C, load: 21.18N): 0.5g/10min)

(Example 1)

A resin composition obtained by mixing (X-1) and (W-1) at a mass ratio of 95:5 was used in the (I) layer, and (A-1) was used as the (II) layer The resin composition mixed with (B-1) at a mass ratio of 95:5 was obtained by using double The T-die method of the shaft extruder, after co-extrusion molding under the condition of resin temperature 180~220 ℃, the casting roll is used for rapid film forming at 20 ℃, and the thickness of each layer is obtained as (I)/(II)/ (I)=0.09mm/0.27mm/0.09mm sheet. Table 1 shows the results of evaluating various properties using the obtained sheet.

(Example 2)

In Example 1, except that the lamination structure is changed to (I) layer/(II) layer, and the thickness of each layer is (I)/(II)=0.09mm/0.36mm, the same as in Example 1 Tablets were obtained in the same manner. Table 1 shows the results of evaluating various properties using the obtained sheet.

(Example 3)

In Example 1, a resin composition obtained by mixing (A-1) and (B-1) at a mass ratio of 80:20 was used as the (II) layer, and the thickness of each layer was (I)/( II)/(I)=0.045mm/0.36mm/0.045mm was changed, and the sheet|seat was obtained similarly to Example 1 except having changed. Table 1 shows the results of evaluating various properties using the obtained sheet.

(Example 4)

In Example 3, it was changed to a resin composition in which the mass ratio of (X-1) and (W-1) in the (I) layer was mixed at a ratio of 90:10, and as the (II) layer, changed to A sheet was obtained in the same manner as in Example 3 except that (A-2) and (B-1) were mixed at a mass ratio of 95:5 to form a resin composition. Table 1 shows the results of evaluating various properties using the obtained sheet.

(comparative example 1)

Using a resin composition mixed with (X-1) and (W-1) at a mass ratio of 95:5, extruded at a resin temperature of 180~220°C by T-shaped die method, and then heated at 20°C The casting roll was used for rapid film forming to obtain a single-layer sheet with a thickness of 0.45mm. Table 1 shows the results of evaluating various properties using the obtained sheet.

(comparative example 2)

In Example 1, except having changed (II) layer into (A-1) 100 mass parts of resin compositions, it carried out similarly to Example 1, and obtained the sheet|seat. Table 1 shows the results of evaluating various properties using the obtained sheet.

(comparative example 3)

The resin composition of (A-1) was changed to a resin composition in which 0.5 parts by mass of a silane coupling agent (manufactured by Momentive, trade name: SILQUEST) was added and dry-blended, except that it was the same as in Comparative Example 1. to obtain single-layer flakes. Table 1 shows the results of evaluating various properties using the obtained sheet.

[Table 1]

Table 1

It can be confirmed from Table 1 that the solar cell encapsulating materials specified in the present invention are excellent in adhesiveness, long-term stability of adhesive force, transparency (total light transmittance), and heat resistance (Examples 1 to 4). On the other hand, it can be confirmed that any one or more of the long-term stability of adhesive force, transparency (total light transmittance), and heat resistance of the encapsulating material that does not have the constitution and material specified in the present invention can be confirmed. The properties were insufficient (Comparative Examples 1 to 3). Specifically, it was confirmed that the transparency (total light transmittance) was insufficient (Comparative Example 1), the heat resistance was insufficient (Comparative Example 2), or the long-term stability of the adhesive force and heat resistance were insufficient (Comparative Example 3).

(Example 5)

Using a vacuum laminator (manufactured by NPC Co., Ltd., brand name: LM30×30), temperature on a hot plate: 150°C, processing time: 10 minutes (details, vacuum: 3 minutes, pressing: 7 minutes), lamination speed : Under rapid conditions, vacuum press sequentially from the hot plate side as the upper protective material as a white plate glass with a thickness of 3 mm (manufactured by Asahi Glass Co., Ltd., trade name: Solite), and the sheet with a thickness of 0.45 mm taken in Example 1 ( encapsulation material), a solar cell with a thickness of 0.4mm (manufactured by Photowatt, model: 101×101MM), a sheet with a thickness of 0.45mm (encapsulation material) taken in Example 1, and a thickness of 0.125mm as a lower protective material A solar cell module (size: 150 mm×150 mm) was produced by five layers of a weather-resistant PET film (manufactured by Toray Co., Ltd., trade name: Lumirror X10S). The obtained solar cell module was excellent in transparency, appearance, and the like.

(Example 6)

As the (I) layer, a resin composition obtained by mixing (X-3) and (Y-1) at a mass ratio of 70:30 was used, and as the (II) layer, (A-3) was used The resin composition mixed with (B-3) at a mass ratio of 95:5 was obtained by using double The T-die method of the shaft extruder, after co-extrusion molding at a resin temperature of 180~200°C, is quenched with a casting roll at 20°C to form a film, and the thickness of each layer is (I)/(II)/( I)=0.09mm/0.27mm/0.09mm sheet. Table 2 shows the results of evaluating various properties using the obtained sheet.

(Example 7)

In Example 6, the (I) layer was changed to a resin composition obtained by mixing (X-3), (Y-1) and (W-1) at a mass ratio of 85:13:2, In addition, a sheet was obtained in the same manner as in Example 6 except that the layer (II) was changed to a resin composition obtained by mixing (A-3) and (B-2) at a mass ratio of 80:20. . Table 2 shows the results of evaluating various properties using the obtained sheet.

(Example 8)

In Example 6, the (II) layer was changed to a resin composition obtained by mixing (A-2) and (B-3) at a mass ratio of 95:5, and the thickness of each layer became (I )/(II)/(I)=0.045mm/0.36mm/0.045mm, except that the sheet was obtained in the same manner as in Example 6. Table 2 shows the results of evaluating various properties using the obtained sheet.

(Example 9)

In Example 6, the (I) layer was changed to a resin composition obtained by mixing (X-3), (X-2) and (Y-1) at a mass ratio of 90:5:5, Furthermore, the sheet|seat was obtained similarly to Example 6 except having changed so that each layer thickness might become (I)/(II)/(I)=0.045mm/0.36mm/0.045mm. Table 2 shows the results of evaluating various properties using the obtained sheet.

(comparative example 4)

In Example 6, a sheet was obtained in the same manner as in Example 6 except that the resin composition constituting the (II) layer was changed to only (A-3). Table 2 shows the results of evaluating various properties using the obtained sheet.

[Table 2]

Table 2

It can be confirmed from Table 2 that the solar cell encapsulating materials specified in the present invention are excellent in adhesiveness, transparency (total light transmittance), and heat resistance (Examples 6 to 9). On the other hand, it was confirmed that the transparency (total light transmittance) and heat resistance of the encapsulating material not having the constitution and material specified in the present invention were insufficient. Specifically, it was confirmed that when the ethylene-α-olefin block copolymer (B) was not contained in the (II) layer, the heat resistance was insufficient (Comparative Example 4).

(Example 10)

Using a vacuum laminator (manufactured by Nisshinbo Co., Ltd., brand name: PVL0505S), temperature on the hot plate: 150°C, processing time: 10 minutes (details, vacuuming: 3 minutes, pressing: 7 minutes), lamination speed: Under fast conditions, white plate glass (manufactured by Asahi Glass Co., Ltd., trade name: Solite) with a thickness of 3 mm as the upper protective material, and the sheet with a thickness of 0.45 mm taken in Example 1 (packaging material), a solar cell with a thickness of 0.4mm (manufactured by Photowatt, model: 101×101MM), a sheet (encapsulation material) with a thickness of 0.45mm taken in Example 7, and a thickness of 0.125mm as a lower protective material A solar cell module (size: 150 mm×150 mm) was produced by five layers of a weather-resistant PET film (manufactured by Toray Co., Ltd., trade name: Lumirror X10S). The obtained solar cell module was excellent in transparency, appearance, and the like.

(Example 11)

For the sheet obtained in Example 9, under the conditions of irradiation intensity: 300W, irradiation speed: 10m/min (corona treatment amount: 60W·min/m ² ), corona treatment was performed on the packaging material, and the thickness 3.2mm, 150mm in length, 150mm in width with embossed whiteboard glass (manufactured by Asahi Glass Co., Ltd., trade name: Solite) and 0.33mm thick fluorine-based backsheet (manufactured by Cybrid Co., Ltd., wetting index: 42mN/m, no sticking Laminate, PVdF/PET/PVdF laminate) A PET film (manufactured by Mitsubishi Plastics Corporation, trade name: Diafoil) with a thickness of 0.012 mm, a length of 90 mm, and a width of 150 mm and a corona-treated film with a thickness of 0.45 mm For the sheet-shaped sealing material, a PET film is used to form the starting point between the glass and the sealing material, and a vacuum laminator (manufactured by Nisshinbo Co., Ltd., trade name: PVL0505S) is used to press at a temperature of 150°C, vacuum for 3 minutes, and press for 7 minutes. After lamination and preparation of samples, a test piece with a width of 10 mm is prepared, the glass is clamped by the chuck of a tensile testing machine (manufactured by INTESCO, trade name: 200X), and the backplane and sealing material are mounted on the other side. The chuck was used to evaluate the adhesive force at an angle of 180 degrees and a tensile speed of 50 mm/min. In addition, the adhesive force was evaluated by the above-mentioned method using a sample produced without corona treatment of the sheet obtained in Example 9, and the effect of corona treatment was compared. The results are shown in Table 3.

(Example 12)

In Example 11, except having changed into the sheet|seat obtained in Example 7, it carried out similarly to Example 11, and evaluated adhesive force. The results are shown in Table 3.

[table 3]

table 3

From Table 3, it was confirmed that the solar cell encapsulant specified in the present invention exhibited excellent adhesion to a fluorine-based back sheet by corona treatment on the encapsulant side (Examples 11 and 12).

Symbol Description

10...transparent substrate

12A, 12B...Encapsulation resin layer

14A, 14B…solar cell elements

16…Backplane

18...junction box

20...wiring

Claims (10)

1. solar cell package material, at least have adhesive layer and be the I layer and be the II layer by the layer that resin combination C consists of, described resin combination C contains the ethene-alpha-olefin random copolymer A that satisfies following (a) condition and the ethylene-a-olefin block copolymer B that satisfies following (b) condition

(a) during means of differential scanning calorimetry was measured, the watery fusion heat of measuring take 10 ℃/minute firing rates was as 0 ~ 70J/g,

(b) during means of differential scanning calorimetry is measured, the crystallization melting peak temperature of measuring take 10 ℃/minute firing rates as more than 100 ℃ and the watery fusion heat as 5 ~ 70J/g.

2. solar cell package material according to claim 1 is characterized in that, described I layer is made of the resin combination take polyolefin-based resins as principal component.

3. solar cell package material according to claim 1 and 2 is characterized in that, described I layer contains ultra-violet absorber and/or weather-proof stabilizer.

4. each described solar cell package material is characterized in that according to claim 1 ~ 3, and described I layer is by containing polyethylene-based resin X and silane-modified vinylite Y and satisfy the I layer that the resin combination Z of following (a) condition consists of,

(a) during means of differential scanning calorimetry was measured, the watery fusion heat of measuring take 10 ℃/minute firing rates was as 0 ~ 70J/g.

5. solar cell package material according to claim 4 is characterized in that, the absolute value of the difference of the mean refractive index of described polyethylene-based resin X and described silane-modified vinylite Y is below 0.0100.

6. each described solar cell package material is characterized in that according to claim 1 ~ 5, and described ethylene-a-olefin block copolymer B is the ethylene-octene segmented copolymer.

7. each described solar cell package material is characterized in that according to claim 1 ~ 6, and it is identical with the kind of the alpha-olefin of described ethylene-a-olefin block copolymer B to consist of described ethene-alpha-olefin random copolymer A.

8. each described solar cell package material according to claim 4 ~ 7, it is characterized in that the kind of alpha-olefin that consists of each described polyethylene-based resin X, described silane-modified vinylite Y, described ethene-alpha-olefin random copolymer A and described ethylene-a-olefin block copolymer B is identical.

9. each described solar cell package material according to claim 1 ~ 8, it is characterized in that, storage modulus E ' in the Measurement of Dynamic Viscoelasticity under the condition of 20 ℃ of vibration frequency 10Hz, temperature is 10 ~ 100MPa, the crystallization melting peak temperature of measuring take 10 ℃/minute firing rate during means of differential scanning calorimetry is measured is as 110 ~ 145 ℃, and total light transmittance is more than 85%.

10. solar module, right to use require in 1 ~ 9 each described solar cell package material to make.

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